Discovery Of Natural Odors- a new way to develop cheaper mosquito repellents !..

Entomologists at the University of California, Riverside (Anandasankar Ray, an assistant professor in the Department of Entomology, and Stephanie Turner, his graduate student)  working on fruit flies in the lab have discovered a novel class of compounds that could pave the way for developing inexpensive and safe mosquito repellents for combating West Nile virus and other deadly tropica. 

The basis for the 'invention' though looks simple, but this finding is of great importance. As for my knowledge goes most of the mosquito repellents are cyclohalothrins, which are a costly affair to prepare [as a synthetic chemist,  I know how difficult its to prepare cyclohalothrins (pyrethroids)  e.g., Allethrin & Permethrin. When I was working in Rallis India Limited, one of my senior colleague was working on Permethrin and I know how difficult to introduce the halo group that too by using florochlorocarbons CFCs (banned chemicals !)]. Congrats Anandsankar Ray, for this interesting achievement. 

When fruit flies undergo stress, they emit carbon dioxide (CO2) that serves as a warning to other fruit flies that danger or predators could be nearby. The fruit flies are able to detect the CO2 and escape because their antennae are equipped with specialized neurons that are sensitive to the gas.

But fruits and other important food sources for fruit flies also emit CO2 as a by-product of respiration and ripening. If the innate response of the fruit fly is to avoid CO2, how then does it find its way to these foods?. The researchers have have identified a new class of odorants – chemical compounds with smells – present in ripening fruit that prevent the CO2-sensitive neurons in the antennae from functioning. In particular two odors, hexanol and 2,3- butanedione, are strong inhibitors of the CO2-sensitive neurons in the fruit fly.

CO2 emitted in human breath is the main attractant for the Culex mosquito to find people, aiding the transmission of these deadly diseases," Ray said. In their  experiments they  identified hexanol, and a related odor, butanal, as strong inhibitors of CO2-sensitive neurons in Culex mosquitoes. These compounds can now be used to guide research in developing novel repellents and masking agents that are economical and environmentally safe methods to block mosquitoes.

Those interested can listen to Anandsankar